Household paper is a common consumable product, but due to psychological demand for whiteness and requirement for some physical indexes, paper is usually mainly prepared from bleached wood pulp, and the prior art gives some technical schemes for preparing the household paper, for example:
CN94105089 relates to complete wheat straw high-efficiency pharmaceutical and healthcare toilet paper, and a process for the complete wheat straw high-efficiency pharmaceutical and healthcare toilet paper of the invention comprises paper manufacturing.
CN200410026132 discloses a method for preparing household paper by compounding collagen fiber and plant fiber, and specifically the method comprises mixing bleached softwood (hardwood) pulp with wheat straw pulp to attain 1-4% mass concentration of the pulp, mixing the bleached softwood (hardwood) pulp and the wheat straw pulp with collagen fiber pulp, and adding a softening agent to a machine chest; then feeding resulting pulp to a paper machine wire after mixing; and pressing, drying, reeling and processing wet paper to obtain a finished product.
Pollution from paper and pulp making industry mainly lies in two steps of treating and discharging black liquor after cooking and bleaching pulp, in which pollution from the pulp bleaching step is particularly obvious. With respect to discharge of conventional chloric bleaching wastewater, wastewater contains common aquatic environment pollution factors such as COD and BOD and other special pollutants. For example, in the case of chlorine bleaching and hypochlorite bleaching, wastewater discharged from bleaching every 1 t of bagasse pulp contains 150-250 g of chloroform produced in hypochlorite bleaching, and wastewater discharged from bleaching every 1 t of wood pulp contains 700 g of chloroform. In addition to chloroform produced in the chlorine bleaching, the wastewater also contains more than 40 organic chlorides in which chlorophenols are the most, such as dichlorophenol and trichlorophenol, and contains dioxins and chlorinated furans, a majority of which are highly toxic. AOX has teratogenetic, cancerogenic and mutagenic hazards.
Developed countries and regions such as Western Europe, Hong Kong, Taiwan, Japan and Korea provide addition of harmful substances to office paper production processes, providing that neither chloric bleacher nor fluorescer can be used, and give mandatory requirement for content of harmful substances in the production process, and Japan controls whiteness (<70%) to avoid excessive use of fluorescers. The standards are that contents of COD and AOX in the wastewater are not more than 20 Kg/t paper and not more than 0.3 Kg/t paper respectively. In order to solve water pollution problem, all enterprises and the society pay a high price.
Toilet paper or household paper is prepared from wheat straw or plant fiber as the raw material in the above reference documents, as pulping method in the prior art is relatively lagged, grass material is always cooked to low hardness during preparing pulp from grass plant as the raw material, for example, the grass materials are cooked to hardness with 11-14 potassium permanganate number. In order to achieve such low hardness, amount of cooking liquor and time of heating and insulation are necessarily much, while high-temperature cooking and insulation in high-concentration chemical liquor certainly causes degradation and damage of cellulose and hemicellulose in the grass material, and inherent length of fiber can not be kept well, thus prepared straw pulp has low strength, and then resulting toilet paper and household paper have low quality. In addition, the bleaching step is necessary in the preparation method of the toilet paper and the household paper in the prior art, produces great pollution to environment and products, and produces dioxins, adsorbable organic halide and other carcinogenic substances, which produces great damages to users; moreover, even though wood pulp is used for preparing a variety of paper in the preparation method of the prior art, the fluorescers and other substances harmful for human health are also added and remained in products more or less, which can cause damages to health of users.
Therefore, the prior art does not describe how to prepare higher-performance pulp suitable for preparing various high-quality paper products with respect to the grass material, for disadvantages of the prior art, in more detail, and for the reason, the invention is proposed.